1. Field of the Invention
This invention relates to an automatic system for controlling coal recovery in the froth flotation process.
2. State of the Prior Art
In the process of fine coal recovery, a coal slurry is passed to a flotation cell to which frother and collector are added to separate the coal from unwanted impurities such as clay. Various methods and apparatus have been used to automatically control the addition of the chemical additives to the flotation cell to optimize cell performance. U.K. Patent Applications GB 2188752A and GB 2182172A disclose comparing sensed solids content of the input stream to the diluted output stream of a froth flotation cell to readjust the addition of chemicals to the cell. U.K. Patent No. 819,868 utilizes a radioactive scanner of the filter cake to control the reagent feeder. U.S. Pat. No. 4,559,134 uses a particle size analyzer to control the addition of the collector.
Other devices such as nuclear densitometers, coriolis effect mass flow detector, magnetic flowmeters, dual bubbler tube densitometers and X-ray diffraction equipment have been used to monitor the flotation process, however, these devices are complicated and expensive and do not provide a simple physical reading of the coal content in the slurry to monitor cell operation.